Detonator leg wire assembly and method of winding the same



Nov. 24, 1936.

' DANlEL D. HUYETT,

Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE DI ETONATOR LEG WIREASSEIVIBLY AND METHOD OF WINDING THE SAME Application December 8, 1934,Serial No. 756,711

5 Claims.

This invention relates to a method of winding the leg wires ofdetonators and it has for its obiect to provide leg wires wound tobundle formation for convenient packaging and in such manner as toinsure the opening out of the leg wires without kinking of the same.

Other advantages of the invention will be set forth in the detaileddescription which follows.

In the accompanying drawing, Fig. 1 is a front view of a pair of spacedpins about which the leg wires are wound in a figure 8 path.

Fig. 2 is a greatly magnified plan view of a part of the uppermost pinof Fig. l.

Fig. 3 is a perspective view of a leg wire bundle consisting of a groupof figure 8 loops.

Figure 4 is a view of the bundle illustrated in Fig. 3 but with theopposite ends of the leg wires drawn away from each other to begin toopen the bundle.

Fig. 5 is a plan view of a portion of a single one of the wires.

Fig. 6 is a diagrammatic view illustrating a method of figure 8 winding,which brings about the kinking that it is the object of the presentinvention to avoid.

Like numerals designate corresponding parts in all of the figures of thedrawing.

The electric blasting caps employed in mining, quarrying, and likeoperations have a pair of leg wires 5 and 6 attached to them, said legwires being covered with insulation, as indicated at I and 8, exceptwhere they are left bare at one end for attachment to the detonator andare left bare at the other end for connection to the main firing cable.It is common practice to wind these leg wires to form a bundle of loopsfor convenient packaging and in the patent of David F. Mc- Farland,1,983,141, issued December 4, 1934, there is illustrated a detonatorpackage in which the leg wires are wound to form a bundle consisting ofa group of figure 8 loops and wherein the winding is conducted in acontinuously advancing path so that each loop lies in a plane separatefrom the plane of any other loop; whereby intertangling of therespective loops is avoided.

A primary feature of the present invention resides in winding detcnatorleg wires to form a plurality of figure 8 loops, the winding beingcarried out in a continuously advancing path so that every loop lies innon-intertwined relation with every other loop and wherein during thewinding the wires are given such a set as will tend to cause them, whenreleased from the restraining packaging means to move toward openposition in that direction which, if continued, will result in the wiresbeing drawn out to straight line position without kinking. Theimportance of the foregoing may be best appreciated by comparing Figs. 4and 6. If the opposite ends of the wire illustrated in Fig. 4 be drawnaway from each other, the entire length of wire may be drawn out tostraight line position Without kinking or tangling while if the samewires were grasped and drawn upon in such manner as to move therighthand ends of the wire toward the left and the lefthand ends of thewires toward the right, we would get the result illustrated in Fig. 6and in which there would be a kinking at every bend of the wire.

In carrying out the invention, the wires are wound upon the mandrels orpins 9 and ill through a continuously advancing figure 8 path from therear end of the pins as indicated at H toward the forward ends of thepins as indicated by arrow I 2. The wires are wound with such longitudinal tension about the mandrels as to impart a permanent set to thebends l3 of the loops, at the point where they pass about the pins ormandrels and by referring to Fig. 5 it will be seen that, due to thecrossing of the wires to form the figure 8 bundle the bends are pitchedin the same direction and forwardly with respect to the direction of thewinding of the wire. The result is that when the winding is completed wehave a bundle consisting of a group of figure 8 loops which lie inplanes separate from each other and wherein the connecting bends betweenthe loops have been given a permanent set at an angle to the generalplane of the whole group of loops and are pitched toward the forward endof the group of loops, the axes of said bends lying at a decided anglewith respect to the general direction of the length of said group ofloops. In packaging the detonators with their attached leg wires, it iscustomary to bind the group of loops firmly together, or, as in theMcFarland patent aforesaid, bind the whole group of loops to or aboutthe detonator. A restraining or tying means is placed about the wholegroup of loops and they are held in the form of a snug or compact bundleuntil the time of use arrives, at which time the miner or other userremoves the restraining means, which may consist simply of the free endsof the wires wrapped about the center of the group or may consist of ahousing pasteboard tube, such as illustrated in the Mc- Farland patent.The method of winding herein described insures that when the restrainingmeans is removed the coils or loops will tend, by reason of the mannerof winding described, to

I strand formation without crossing at any of the] the kinking move inthat direction which if continued will bring about the extension ottheloopsto single bends and consequently which would result from suchcrossing as indicated in Fig. 6.

In carrying 'out'the winding herein described, the wire. is permitted,while being given the necessary longitudinal tension, to pass freelythrough the winding shuttle so -that no cross sectional twist or torsionis imposed upon the wires at any point. I have found that if anytorsional twist.

is imposed upon the wires during winding, it tends to cause the wires tomove to crossed position, as indicated inFig. 6. Therefore, I combinewith the provision of the initial set of theJoends. freedom fromtorsional strains. It may seem that there would never be any reason fordrawing the left-hand end of the wire in Fig. 4 to the right and viceversa, but it should be remembered that in the absence of any means fordetermining which way the bundle is to be opened, the operator wouldhave in his hand upon removal of the restraining means merely a groupof. loops and he would be almost as likely to draw these groups of loopsout in one direction as in the other. The present invention aids theoperator in determining how to grasp and in which direction to draw uponthe group of loops.

Having described my invention, what I claim is: 1. The herein describedmethod of winding detonator leg wires which consists of winding therelatively soft .wire commonly employed for said leg wires under tensionto form a group of figure -8 loops wherein each loop lies in a planeseparate from adjacent loops and wherein the connecting bends betweenthe loops are formed-under such tension as to impart a permanent set tothe bends of the loops at an angle to the general plane of the wholegroup of loops and pitched toward the forward end of the group of loopswith the axes of said bends lying at an angle with respect to thegeneral direction of the length of the group of loops whereby when saidgroups of loops are released from restraint they tend to open out in adirection which, if continued, would bring all of the wire to singlestrand formation without kinking.

2. The herein described method of winding the leg wires of detonatorswhich consists of winding the relatively soft wire commonly employed forsaid leg wires to form a group of figure 8 loops .wherein each loop liesin a plane separate from wherein each loop lies in adjacent loops andwherein the connecting bends between the loops are'formed under suchtension as to impart a permanent-set to the bends oi the loops to causethem to lie at an angle to the general plane of the whole group of loopsand pitched toward the forward end of the group of loops, said wiresbeing wound under the necessary longitudinal tension but substantiallywithout torsional twist in such direction as would tend to cause thewires to cross at the bends whereby when said groups of loops arereleased from restraint they tend to open out in a direction which, ifcontinued, would bring all of the wire to single strand formationwithout kinking.

3. A bundle; of detonator leg wires formed of relatively soft wire andconsisting of a group of loops wound in a continually 'advancingdirection and in figure 8 form and wherein the bends of said loops havea permanent set at an angle to the general plane of the whole group ofloops and pitched toward the forward end of the group of loops so thatthe axes of said bends lie at an angle with respect to the generaldirection of the length of the group of loops whereby when said groupsof loops are released from restraint they tend to open out in adirection which, if continued, would bring all of the wire to singlestrand formation without kinking.

4. A bundle of detonator leg wires as recited in claim 3 wherein thesaid wires are wound under such longitudinal tension as to impart thedescribed set to the wires while leaving them free of torsional set.

5. The herein described method of winding the relatively soft wirecommonly employed for the leg Wires of detonators which consists ofwinding said wires to form a group of elongated loops a plane separatefrom adjacent loops, wherein the connecting bends between the loops areformed under such longitudinal tension as to-impart a permanent set tothe bends of the loops to cause them to lie at an angle to the generalplane of-the whole group of loops, but wherein the winding shuttle forthe wires engages the same in such manner as to permit the wires to passfreely therethrough without imparting any cross-sectional twist to saidwires whereby when said groups of loops are released from restraint theytend to open out in a direction which, if continued, would bring all ofthe wire to single strand formation without kinking.

DANIEL n. HUYETT.

